Develop and maintain animal models, with particular emphasis on mice of known genetic background, which help elucidate the biochemical (i.e., gene dose effect), developmental, and phenotypic consequences of trisomy, exemplified by Dwon Syndrome. Describe the biochemical consequences of chromosome imbalance in the animal model and correlate them to analogous biochemical findings in the human. The evaluation should also be on their effects on brain development and function.